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vfork.S

vfork.S 1.9 KB
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  1. /* Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
    2. 

  2.    This file is part of the GNU C Library.
    3. 

  3. 

  4.    The GNU C Library is free software; you can redistribute it and/or
    5. 

  5.    modify it under the terms of the GNU Lesser General Public
    6. 

  6.    License as published by the Free Software Foundation; either
    7. 

  7.    version 2.1 of the License, or (at your option) any later version.
    8. 

  8. 

  9.    The GNU C Library is distributed in the hope that it will be useful,
    10. 

  10.    but WITHOUT ANY WARRANTY; without even the implied warranty of
    11. 

  11.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    12. 

  12.    Lesser General Public License for more details.
    13. 

  13. 

  14.    You should have received a copy of the GNU Lesser General Public
    15. 

  15.    License along with the GNU C Library; if not, write to the Free
    16. 

  16.    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    17. 

  17.    02111-1307 USA.  */
    18. 

  18. 

  19. #include <sysdep-cancel.h>
    20. 

  20. #define _ERRNO_H	1
    21. 

  21. #include <bits/errno.h>
    22. 

  22. 

  23. /* Clone the calling process, but without copying the whole address space.
    24. 

  24.    The calling process is suspended until the new process exits or is
    25. 

  25.    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
    26. 

  26.    and the process ID of the new process to the old process.  */
    27. 

  27. 

  28. ENTRY (__vfork)
    29. 

  29. 

  30. #ifdef SHARED
    31. 

  31. 	cmpq	$0, __libc_pthread_functions(%rip)
    32. 

  32. #else
    33. 

  33. 	.weak	pthread_create
    34. 

  34. 	movq	$pthread_create, %rax
    35. 

  35. 	testq	%rax, %rax
    36. 

  36. #endif
    37. 

  37. 	jne	HIDDEN_JUMPTARGET (__fork)
    38. 

  38. 

  39. 	/* Pop the return PC value into RDI.  We need a register that
    40. 

  40. 	   is preserved by the syscall and that we're allowed to destroy. */
    41. 

  41. 	popq	%rdi
    42. 

  42. 	cfi_adjust_cfa_offset(-8)
    43. 

  43. 

  44. 	/* Stuff the syscall number in RAX and enter into the kernel.  */
    45. 

  45. 	movl	$SYS_ify (vfork), %eax
    46. 

  46. 	syscall
    47. 

  47. 

  48. 	/* Push back the return PC.  */
    49. 

  49. 	pushq	%rdi
    50. 

  50. 	cfi_adjust_cfa_offset(8)
    51. 

  51. 

  52. 	cmpl	$-4095, %eax
    53. 

  53. 	jae SYSCALL_ERROR_LABEL		/* Branch forward if it failed.  */
    54. 

  54. 

  55. 	/* Normal return.  */
    56. 

  56. .Lpseudo_end:
    57. 

  57. 	ret
    58. 

  58. 

  59. PSEUDO_END (__vfork)
    60. 

  60. libc_hidden_def (__vfork)
    61. 

  61. 

  62. weak_alias (__vfork, vfork)
    63.